Dr Henning Allmers believes Manfred von Richthofen was probably not fit to fly during the last months of his life after being shot in head in July 1917.

The Baron was advised by doctors not to fly until the head wound had completely healed. He had suffered severe concussion of the brain and probably internal bleeding.

However, von Richthofen, who shot down 80 allied planes during his career as a fighter pilot, was so determined to rejoin the fray that he spent just 20 days in a field hospital before rushing back into active service.

The baron's bravery proved to be his undoing. Just eight months after resuming his flying duties he was shot down and killed.

Writing in the Lancet medical journal, Dr Allmers, from Dortmund, pointed out that when von Richthofen discharged himself from the field hospital his skull wound was not closed.

Medical note

The Red Baron shot down 80 British planes

The medical note added: "Sudden changes in air pressure during flight might lead to disturbances of his consciousness".

Nevertheless von Richthofen returned to flying duty on 18 August 1917 and was credited with his 58th aerial victory the same day.

He was almost sick during this first flight after the injury and on 27 August 1917 another piece of bone was removed from the open would which was still more than 2cm across.

There is also evidence that von Richthofen suffered depression after the near fatal shooting, said Dr Allmers.

He added: "I believe that the Red Baron should not have been declared fit for duty after the head wound he received on 6 July 1917."

But Dr Allmers noted that a "hero" such as von Richthofen could not have been grounded against his wishes for public relations reasons.